Device for determining the fill level of a medium in a container

ABSTRACT

A device for determining the fill level of a medium in a container has at least one electronic device and at least one signal conductor arrangement. The electronic device supplies the signal conductor arrangement with electromagnetic signals. To provide a device for determining the fill level that is advantageous compared to the prior art, the signal conductor arrangement has several emitting devices for emitting the electromagnetic signal. A support element that can be inserted in a wall of the container supports the signal conductor arrangement.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for determining the fill level of amedium in a container that has at least one electronic device and atleast one signal conductor arrangement. The electronic device suppliesthe signal conductor arrangement with electromagnetic signals. Themedium is, for example, bulk goods or a liquid and the container is, forexample, a tank, a silo or a channel. The signals are, in particular,high frequency or microwave signals.

2. Description of Related Art

It is known in industrial process automation either to continuallymeasure the fill level of the medium or to specifically monitorparticular limit levels.

Such devices for monitoring limit levels are also called fill level orlimit level switches. They are used, for example, depending on themounting position, for overflow protection, idle state protection orpump protection.

If the medium reaches a predetermined fill level or falls below such,the switches generally generate a signal that, e.g., interrupts a fillprocess or triggers a safety mechanism or causes the closing of a drainvalve.

It is known, for example, to detect limit levels capacitively (e.g.,German Patent Application DE 100 23 850 A1), using conductivitymeasurement (e.g., International Patent Application Publication WO97/37198 A1 and corresponding U.S. Pat. No. 5,861,811) or usingmechanically swingable sensors (e.g., German Patent Application DE 19825 501 A1).

Furthermore, a device is known from International Patent ApplicationPublication WO 2013/167384 A1 and corresponding U.S. Patent ApplicationPublication Patent 2015/082881 for detecting a limit level of a medium,in which the frequency of an output signal of a resonator is evaluated.The resonator is in contact with the interior of the chamber thatcontains or conducts the medium. Detection thereby occurs in that thefrequency of the resonator is exploited depending on the dielectricconstant of the medium. In one design, the resonator is designed as amicro strip line or as an emitting device.

It is known from a completely different field of application todetermine the moisture of objects in a container using reflectorswitches, see German Patent Application DE 10 2004 016 725 A1.

A strip line antenna for fill level recognition is, for example,provided in German Patent Application DE 199 35 743 A1. Thereby, in onedesign, two receivers for microwave signals are used for the redundantmonitoring of the fill level.

An exemplary design of emitting devices that are used in the field offill level measurement is disclosed in German Patent Application DE 102006 019 688 B4 and corresponding U.S. Pat. No. 7,710,328. Such emittingdevices are made, in general, of metal surfaces that are present on orin printed circuit boards or other substrates.

It is additionally known in the prior art to further add metal surfacesacting as reflectors.

So-called patch antennae are also known in the prior art (other termsare “flat antenna” or “micro strip antenna”). An array is created byinterconnecting several antennae. It is thereby known to createdifferent resonance structures: half-wave or quarter-wave, see, e.g.,German Patent Application DE 699 36 903 T2 and corresponding U.S. Pat.No. 6,218,990. Panel antennae can be used for measuring the surfacestructure of media, see e.g., European Patent Application EP 1 701 142A2 and corresponding U.S. Pat. No. 7,408,501.

Panel antennae that are arranged in ceramic structures are used for filllevel recognition, for example according to International PatentApplication Publication WO 2009/121530 A1 and corresponding U.S. Pat.No. 8,474,314.

In the fill level switch according to European Patent Application EP 1956 349 A2 and corresponding U.S. Pat. No. 7,730,780, electromagneticsignals are coupled into each of a measuring conductor arrangement and aresonance conductor arrangement, wherein the signal of the measuringconductor arrangement can interact with the medium, whose fill level isto be monitored.

A device having microwave sensors for the specific use of monitoring thefill level of a blood reservoir is described in German PatentApplication DE 195 16 789 B4. These sensors are attached outside of thereservoir and radiate through its wall. It is described, in one design,that several sensors are attached at the same level. It is furtherprovided that sensors are attached at different levels in order toalready be able to signal that the fill level is approaching a criticallimit level.

Contaminants or the deposition of medium on the container wall orespecially on the sensors are problematic for the above-mentioneddevices or, respectively, limit level switches. This can lead to falsesignals or can even prevent the detection of the reaching or fallingbelow a fill level.

Originating from these problems, it is known, for example, in membraneoscillators to shake off gas bubbles during a cleansing phase (seeGerman Patent Application DE 10 2008 050 445 A1).

In safety-critical uses, it is further known to design the sensors ordevices redundantly. In the simplest case, two measuring devices areused that have the same function.

In particular, the following types of redundancy are therebydifferentiated:

In hot spare, several sensors are actively operated. A so-called voterevaluates the individual results, wherein, if necessary, the majoritydecides.

In cold redundancy, several sensors are present, however, only onesensor is active. Based on the evaluation of the signals of thisindividual sensor, further sensors are activated, if need be.

In standby or passive redundancy, again, several sensors are presentand, again, only one sensor is active. The non-active sensors arethereby in a standby state. In the case of an error of the activesensor, another sensor is switched on.

Thereby, the redundancy can be homogeneous or diverse. This means, forexample, that either the same type of sensor or the same components aremultiply used, or that the individual sensors or components come fromdifferent producers or are based on different principles.

SUMMARY OF THE INVENTION

The object of the invention is to provide a device for determining thefill level that is advantageous compared to the prior art.

The device according to the invention in which the above derived anddescribed object is achieved, is initially and essentially wherein thesignal conductor arrangement has several emitting devices for emittingthe electromagnetic signal, that a support element at least partiallysupports the signal conductor arrangement and that the support elementcan be inserted in a wall of the container.

In one design, the support element is designed as a flange.

The device according to the invention is, in particular, a so-calledlimit level switch that shows whether or not the medium has reached orfallen below a fill level—i.e., a limit level.

The device according to the invention detects the fill level of themedium in that a signal conductor arrangement is supplied withelectromagnetic signals and in that it is identified whether the mediumcovers the signal conductor arrangement.

Thereby, the signal conductor arrangement has several emitting devices,which are each supplied with the electromagnetic signals.

Redundancy, for example, can be created by the plurality of emittingdevices. Furthermore, several level limits can be identified. It isadditionally possible to verify measurement values.

The signal conductor arrangement, i.e., the emitting devices, is therebyattached in or on a support element. The support element serves as asubstrate for supporting a mechanical structure or for easier mountingof the plurality of emitting devices.

The emitting devices are located, at least in part, in particular, onthe side of the support element facing the medium—in the mounted stateor are at least attached into or on the support element so that aninteraction with the medium can take place.

In one design, the emitting devices are separately created componentsthat are introduced to or deposited on the support element after theirproduction.

In a further design, the emitting devices are first created in or on thesupport element.

The support element is thereby designed, in particular, so that it canbe inserted into a wall of the container. The support element can thusbe inserted, in particular, into a corresponding recess in the wall, forwhich the dimensions need to be compatible.

Since the device is, preferably, a limit level switch, the supportelement can preferably be inserted into a side wall of the container.

In one design, the support element can be screwed into the wall. In thisdesign, the overall result is a fill level or limit level switchdesigned as a screw-in sensor.

Due to the—at least two—emitting devices, it is detected whether themedium is located close to the respective emitting device or,respectively, covers it. Therefore, depending on the use, the reachingor falling below a fill level assigned to the respective emitting devicecan be detected.

Depending on the location at which the individual emitting device islocated in the mounted state in the container wall, i.e., depending onthe installation site, one fill level is monitored by each of theemitting devices.

The fill levels thereby can be different, can be essentially the same,can overlap—depending on the desired measuring accuracy—, or can beadjacent to one another.

Thus, in one design, fill level ranges are defined that are commonlymonitored by several emitting devices.

Which fill levels are assigned to the individual emitting devices, onthe hand, is determined by the dimensioning and arranging of theemitting devices on the support element as well as by the achievablelocal resolution of the measurements and, on the other hand, isdetermined by the end position of the emitting device after assembly.

On that basis, it is provided in one design that the processing of theindividual results or individual measurements or, respectively,individual fill level monitoring of the individual emitting devices isadapted to the specific use or, respectively, to the orientationresulting after assembly in relation to the container and is notpreviously specified.

Due to the plurality of emitting devices, redundancy can, on the onehand, be created in that at least two emitting devices monitor the samefill level or fill level range.

For this, in one design, at least two emitting devices are attachedrelative to a longitudinal axis of the support element at the samelevel. In the mounted state in the container, the longitudinal axis canthereby deviate from a longitudinal axis of the container.

Redundancy is configured in this design when the emitting devices in theattached state are located at the same level in the container.

If they are located at different levels of the container, then they areassigned a different fill level, whose reaching or falling below theymonitor.

In an additional or alternative design, at least two emitting devicesare attached at different levels in relation to a longitudinal axis ofthe support element. The arrangement of the emitting devices therebyrelates to the production of the device and not necessarily to themounted state in the container.

If the emitting devices are located at different levels, different filllevels can be identified by them, or it is possible to identify theapproaching of the medium to a certain level limit. It is thereby alsovalidated whether the limit level has been reached, since—in the case ofthe use as overflow protection—a lower-lying fill level of the mediumhas to be reached.

Depending on the mounting position, however, the emitting devices can beassigned a same fill level or fill level range. In each case, thisdepends on how the support element is inserted in the wall of thecontainer or what the end position of the support element is.

Dynamic measurements or plausibility checks of the individual measuringsignals allow for the detection of different fill levels. Accordingly,the reliability of fill level determination can thereby be respectivelyincreased.

A plurality of individual sensors that are—at least in part—operatedindividually and thus can supply individual measured values (or, inparticular, switching signals) thereby result in the device for filllevel determination due to the individual emitting devices.

Thus, the invention also relates to a measuring arrangement having acontainer and a device for determining the fill level attached to a wallof the container. Thereby, the device described here can also, inparticular, be called limit level switch in this context.

The materials of the support element are adapted thereby to the use orto the respective medium.

In one design, the emitting devices are supplied with the same signalsand in a further design, they are supplied with different signals.

In one design, at least one of the emitting devices is an antenna. Theantenna is, for example, a miniaturized horn antenna.

In a further design, at least one of the emitting devices is a patchantenna. The patch antenna is comprised of a corresponding conductorstructure, as it is known from the prior art.

In particular, in one design, all emitting device are designedessentially identically. Thus, in this design, the emitting devices areeither antennae or, in particular, patch antennae.

The conductor structures or antennae thereby consist, at least in part,of a metal such as, e.g., copper, silver, gold, or nickel.

In that the emitting devices are arranged on a common support element orsubstrate, or generally close to one another, there is a risk that theantennae couple with one another.

The following examples are possible variations for de-coupling:

In one variation, metal surfaces (particular designs are also called“via fences” or “picket fences”) are arranged between the individualemitting devices. In such a separation, a completely parallel operationof all emitting devices is possible.

Further separation is implemented in one design in that differentrunning lengths are created for the signals between a signal source andthe individual emitting devices. Thereby, a signal coming from thesignal source reaches the emitting devices at different points in time.

A parallel operation of all emitting devices is only conditionallypossible in the case of such a temporal separation. Due to therapid—compared to typical change of the fill level—method of detection,the measurements via the individual emitting devices occur quasisimultaneously.

A separation in the frequency range is further or additionally providedin that the emitting devices are supplied with signals having differentfrequencies.

Additionally or alternatively, the emitting devices differ from oneanother in view of their resonance frequency due to their geometry ormaterials, so that this already denotes a de-coupling.

In one design, a further separation is achieved by code multiplexing.Thereby, the signals of the signal source are encoded, wherein eachemitting device is assigned one code sequence.

Thus, in one design, a filter is located in front of the emittingdevices, which allows the signals to pass to the respective emittingdevice according to their code sequence. The same occurs in front of thereflector switches, so that only the respective suitable returningsignals are evaluated.

In one design, at least a portion of the emitting devices differs fromanother portion at least in view of the spatial polarization of therespectively emitting electromagnetic signals. The individual emittingdevices, thus, each have different preferred polarization and emitsignals having different spatial polarization.

In one design, emitting devices have polarization that is at rightangles to the adjacent device.

In one design, further structures are provided for de-coupling, so thata portion of the emitting devices, in particular also in conjunctionwith a spatial gap, emits signals with the same polarization.

It is provided in one design that at least a portion of the emittingdevices is arranged essentially rotationally symmetrical in relation tothe support element.

In one design, the support element is separated into several anglesections on one side, in each of which at least one emitting device islocated.

The angle sections, in particular, have the same size in one design.

If, in this design, a subcategory of n emitting devices from a total ofm emitting devices is distributed evenly over a support element—that iscircularly designed, at least in this area that supports the emittingdevice—then each of the n emitting devices is assigned an angle sectionof 360°/n.

At least one further emitting device, in one design, is located in themiddle of the support element or in the middle of the rotationallysymmetrical arrangement of emitting devices, which thus also representsthe center of the arrangement of—preferably rotationally symmetricallyarranged—emitting devices.

In an alternative design, the middle is free of emitting devices.

In an additional design, more than one emitting device is arrangedcentrally on the support element.

The rotational symmetry is, in particular, advantageous with the designof the support element in that the support element is screwed into thewall of the container. Thus, any free rotation is possible and apredetermined end position does not necessarily have to be achieved.

In one design, the support element is essentially disk-shaped. This formmakes the insertion into the wall of the container easier.

Thereby, the form of the wall or a recess in the wall and the outergeometry of the support element are attuned to one another such thatscrewing in—preferably with a sealing function—is possible.

In order to attach the support element in the container, it is providedin one design that the support element has an outer surface designed asan outer threading. The type of threading is, thereby, to be matched toan inner threading of a recess in the container wall or possibly to anadapter to be correspondingly provided.

In an alternative or additional design, the support element can besealingly inserted into the wall of the container.

In one design, the support element can be screwed so tightly into thewall, that a sealing function results.

In a further variation, at least one sealing lip is provided and in anadditional variation, recesses are provided for sealing elements, e.g.,O-rings or for the insertion of a sealing material.

In a further design, an adapter is provided, which, in particular,allows an alignment of the support element or the emitting devices inrelation to the container.

The support element is formed, at least in part, of a multi-layerceramic, wherein at least a portion of the emitting devices is arrangedbetween the individual layers of the multi-layer ceramic. The emittingdevices are thus protected from the medium by the support element.However, the support element is thereby designed in such a manner thatan interaction between the emitting device and the medium is stillpossible.

In one design, the support element is formed at least in part of aceramic and/or of a plastic and/or of glass.

Additionally or alternatively, the support element is formed, at leastin part, of a circuit board material or of a HF substrate.

In one design, the support element is produced essentially entirely ofone of the above-mentioned materials.

In one design, wherein the support element is of ceramic, the emittingdevices and also the supply and outlet lines are generated e.g., using athin- or thick layer method.

In a further design, the support element is designed to be flat, atleast on the side facing the medium.

In an alternative design, the support element has a convex or concavecourse on the side facing the medium.

The outer contour of the support element contributes to the medium orpossibly occurring condensate flowing or dripping from the supportelement.

In one design, the device allows for use in an area at risk forexplosion. For this, in particular, the components and especially theemitting devices are accordingly dimensioned and designed.

Thus, in one design, it is particularly provided that a—electricallynon-conductive—surface facing the medium or the process has a maximumsize of 4 square centimeters.

Alternatively, the electrically non-conductive part of the surface ofthe support element facing the medium is surrounded by a metallic,grounded structure, wherein the projection surface of this framedsurface is less than 16 square centimeters.

In order to protect the emitting device from the medium or from theprocess conditions prevailing in the container, at least one protectivelayer is provided in one design.

The protective layer is thereby applied in the direction of the mediumor process or container interior in front of an emitting device or infront of the entirety of the emitting devices.

In one design, the protective layer is dielectric.

In one design, the protective layer is a coating.

Depending on the design, the protective layer thereby is formed, atleast in part, of a diamond-like carbon material (DLC coating) and/or ofa polytetrafluoroethylene (PTFE) and/or of glass.

In a further design, the protective layer is formed of a silicon oxide(e.g., silicon monoxide or dioxide).

In order to prevent the medium from adhering, it is provided in onedesign that the protective layer at least partially exhibits the lotuseffect.

Furthermore, the protective layer in one design is at least partiallyporous and in an additional or alternative design is at least partiallyclosed.

In one design, it is provided additionally to the signal conductorarrangement having several emitting devices that the electronic deviceprovides a measure for an emitting behavior of at least one emittingdevice.

The electromagnetic signals are, in particular, microwave signals. Thus,in one design, the device according to the invention can, in particular,be called a high frequency (HF) fill level switch.

The emitting devices, of which at least two are present and which alsocan be called individual elements of the HF fill level switch, are to beunderstood as impedance converters in one design.

Thereby, the wave impedance of a line, via which the electromagneticsignal is supplied to the emitting devices, is adapted to the waveimpedance of the area in front of the emitting devices. This area is, inparticular, a free space in the case that the device is used as overflowprotection.

In that the impedance matching is monitored, it can be assumed that whena change in the matching occurs, a change in the space in front of theemitting device has occurred. In the case of the use as a limit levelswitch, this is a change in the degree of coverage.

The emitting devices are, in one design, designed as antennae and, in afurther design, in particular, are designed as patch antennae.

Preferably, the emitting devices or patch antennae are designed to beflat.

The emitting devices preferably have a relatively narrowband impedancematching.

In patch antennae, as exemplary design for emitting devices, such anarrowband impedance matching can be ascribed to the half-wavelengthresonance being implemented via a patch antenna. Thereby, only thefrequency whose half-wavelength is as large as the geometric length ofthe patch antenna experiences impedance matching.

In one design, the emitting devices are designed in such a manner thatthe direction of emission is orthogonal to both directions of expansionof the emitting device designed as antenna.

The materials surrounding the respective emitting device or therespective patch antenna are important for impedance matching, since thematerials shorten the wavelength of the signal, for which impedancematching occurs, by the root of the effective permittivity.

The permittivity, commonly denominated with the Greek lowercase epsilone, is also called dielectric conductivity or dielectric function anddescribes the permeability of a material for electrical fields.

The link between material permittivity and impedance matchingcharacteristic is used in the device according to the invention in orderto identify the fill level of the medium in a container.

If the material (e.g., due to an exchange of air to the medium toactually be detected), and thus also the permittivity, in front of anemitting device or, in particular, in front of a patch antenna changes,then the effective permittivity around the antenna/emitting devicechanges as does the frequency that represents an impedance matching forthe emitting device.

Thus, on the other hand, if a change in the impedance matching isrecognized by the device according to the invention, then this can beascribed to a change in the fill level.

Additionally or alternatively, a change in the material characteristicsis concluded.

The above correlations can also be described in other words as followsfor the exemplary use as overflow protection:

If an emitting device is supplied with an electromagnetic signal, whosefrequency is the same as the resonance frequency that is set by theemitting device not covered by medium, i.e., free, and if the emittingdevice is not covered by medium during supply with the signal, then thesignal is emitted in the interior of the container, which is, e.g., atank.

Since, in this case, no or very little reflection occurs on the emittingdevice designed as antenna, the energy of the wave returning from theemitting device is extremely small.

If the fill level of the medium in the container changes so that theemitting device is reached, then the resonance frequency of the emittingdevice is also shifted. However, the supplied electromagnetic signalthereby experiences a stronger reflection, which in turn results in agreater energy of the returning wave.

Depending on the magnitude of change of permittivity that results fromthat transition between a free emitting device and one covered withmedium, the emitting device emits at a different, neighboring frequency(small permittivity change) or there is no longer any emission (largepermittivity change).

The described effect can be understood as a near field effect of theantenna or, respectively, the emitting device.

The measure for emitting behavior of at least one emitting devicedetermined by the electronic device is formed, in one design, ofidentifying that the resonance frequency of the at least one emittingdevice has changed. Based on this change, it can then be concluded thatthe degree of coverage of the emitting device by the medium in thecontainer has changed or that a change in the medium itself exists.

Due to the plurality of individually operable emitting devices, severalindividual results are available that can be combined for determiningthe fill level.

The measuring results of the—in particular, of all—emitting devices are,thus, in one design, processed into one overall result using a suitableprocessing unit (e.g., a measuring device or, in general, an electronicsunit), which is implemented by a microprocessor. In another design, theindividual results are consolidated using logical units.

The following designs relate to advantageous designs of the device thatare used, in part, for implementing the above-described correlations.

It is provided in one design that the electronic device evaluates atleast one impedance behavior of the at least one emitting device as ameasure for the emitting behavior of at least one emitting device.

In this design, the electronic device preferably monitors the impedancematching of at least one emitting device.

If the impedance matching changes, this is, in one design, ascribed to achange arising in front of the emitting device, i.e., in particularwithin the container and thus on the emitting side of the emittingdevice. This change is thereby interpreted, in particular, as a changein fill level and is signalized as such.

In an associated design, the electronic device determines an impedancevalue and/or a change of an impedance of at least one emitting device.

In one design, the electronic device determines an absolute value forthe impedance and, additionally or alternatively, determines whether theimpedance has changed.

In one design, at least one input reflection of the at least oneemitting device is determined by the electronic device for the measureof the emitting behavior. In this design, the electronic deviceevaluates the input reflections of at least one emitting device thatyields signals as a result of the supply with electromagnetic signals.The reflection is thus, in this design, a measure for adapting theelectromagnetic signals to the present resonance conditions.

In one design, the electronic device supplies at least one emittingdevice with electromagnetic signals of a predeterminable frequency.

The frequency, in one design, depends on whether the device according tothe invention is used as overflow protection or as idle stateprotection, i.e., whether a change from uncovered to covered state orfrom covered to uncovered state is to be detected.

In a further design, the frequency depends on the materialcharacteristics (such as e.g., permittivity) of the material surroundingthe emitting device. This, thus, also relates to the nature of thesupport element or to a possibly existing protection layer.

If all emitting devices are located in or on one support element, thenthis simplifies the assembly in the process area due to the reduction toone mechanical component.

In one design, several emitting devices are supplied with the sameelectromagnetic signal.

In one design, the predeterminable frequency of the electromagneticsignals corresponds essentially to the resonance frequency of theemitting device not covered by medium. In this design, it is detectedwhen the medium reaches the relevant emitting device, i.e., overflowprotection takes place.

In an alternative design, i.e., in particular when used as pumpprotection or idle state protection, the predeterminable frequencyessentially corresponds to the resonance frequency of the emittingdevice covered by the medium.

If the medium in front of the emitting device changes or if the emittingdevice is no longer covered by medium, then the frequency of the signalssupplied to the emitting device no longer corresponds to the currentresonance frequency. This can be accordingly detected by the electronicdevice and identified or signalized.

In an additional or alternative design, the electronic device varies thefrequency of the electromagnetic signals that are supplied to anemitting device or several emitting devices within a predeterminablefrequency band. In this design, a frequency sweep is carried out and thefrequency behavior of the emitting device or emitting devices ismeasured thereby. This allows for a very exact determination of thecurrent resonance frequency, for example in a plurality of measuringsurroundings or process conditions, which in turn can be informativeabout the surroundings and thus also about the measuring medium.

t is provided in one design that the electronic device has at least onereflector switch for the actual determination of the fill level by theindividual emitting devices, i.e., whether the fill level has beenreached or not.

Thereby, the reflector switch is assigned to one emitting device.

Furthermore, the reflector switch is designed in such a manner that isprovides a measure for an emitting behavior of an emitting device.

The reflector switch detects whether the emitting device is covered bythe medium or whether, e.g., gas or common ambient air is located infront of the emitting device.

The measure for the emitting behavior, in one design, is found in theinformation of whether or not the medium covers the emitting device.

The following exemplary designs are given for the reflector switches or,in general, the metrological design of the electronic device.

The respective emitting device is continuously supplied with amono-frequency signal in an absolute value CW (continuous wave)detection. The frequency is chosen in one design so that it correspondsto the resonance frequency of the emitting device in the case that themedium does not come into contact with the antenna. Thus, if the antennais free, it emits the electromagnetic signal.

The reflector switch thus permanently monitors the adapting of theantenna at the set supply frequency.

In one design, the reflector switch issues a DC voltage that isdependent on the relation between the power supplied to the antenna andthe reflected power.

A comparator that is downstream from the reflector switch in theelectronic device compares, in one design, the generated DC voltage fromthe reflector switch with an external predetermined reference voltageand generates an evaluation.

If there is no medium or ambient air in front of the antenna—when usedas overflow protection, i.e., detecting when the fill level has beenreached—then the antenna is adapted and its input reflection is small.Thus, the reflector switch generates a voltage that is below thereference voltage so that the comparator issues a low level.

If the medium is located in front of the antenna—in the above-mentioneduse—the resonance frequency is shifted and the antenna has a worseadapting behavior for the applied frequency of the signal. Thus, theinput reflection of the antenna is increased and, thus, also the DCvoltage generated by the reflector switch. If the DC voltage is greaterthan the reference voltage, the comparator issues a high level thatsignalizes that the limit level has been reached.

In the case, that the respective emitting device is covered by aprotective layer, or in the case that the medium to be detected has avery low permittivity, it is provided in one design that theabove-described absolute value CW detection is broadened to a complexdetection.

Thereby, as an addition to the above design, both the signal supplied tothe emitting device as well as the reflection signal tapped by theantenna are separated. In addition to the above-described simplereflector switch, both signals are also supplied to a second measuringor evaluating site. A 90° phase shifter is thereby provided in one ofthe two signal paths.

The above-mentioned reflector switch supplies the “in-phase” signal andthe second measuring site supplies the “quadrature” signal.

Both signals are preferably digitized, in one design, for example, inorder to be further processed in a microprocessor. Hereby, a phaseevaluation of the reflected signal is then possible. This has theadvantage that the phase shift due to the reflection of the signal onthe medium is a very sensitive measure.

In the case, in which the medium causes large losses of the signal ofthe emitting devices, the adaptation curve of the antenna broadens overthe frequency.

In order to still reliably detect the reaching of a limit level, it isthus provided that, in one design, a broadband adaptation curve of theemitting devices is determined, i.e., measured.

Thus, in one design, the emitting devices are supplied with signals thatlie within a predeterminable frequency range.

The DC voltage of the respective reflector switch is directly digitizedin one design. This allows for the respective value of the reflection tobe assigned to the frequency of the signal that is supplied to therespective emitting device.

After a complete frequency sweep, the obtained adaptation curve isevaluated, wherein the lowest determined DC voltage of the reflectorswitch is assigned to the resonance frequency of the emitting device.

In one design, the broadband detection is combined with the abovedescribed complex variation and the phase evaluation possible therewith.

In one design, the signal that is supplied to the assigned emittingdevice is supplied to the reflector switch.

In one design, the reflector switch monitors the adaptation of at leastone emitting device during supply with the electromagnetic signal.

In one design, the reflector switch is assigned only to one, singleemitting device, in that the reflector switch is assigned to exactly oneemitting device and provides a measure for the emitting behavior of onlythe one emitting device.

In a further design, each emitting device is assigned one reflectorswitch. Thus, in this design, the number of emitting devices is the sameas the number of reflector switches.

In another design, the at least one reflector switch is assigned toseveral emitting devices and provides at least one measure for theemitting behavior of the emitting devices assigned to it.

The individual reflector switches each generate information aboutwhether—depending on the type of use—the medium has reached or fallenbelow the fill level assigned to the emitting device. The individualresults of the reflector switch are then processed or, respectively,completely evaluated in the electronic device.

In one design, the electronic device is designed such that, after anemitting device is supplied with at least one electromagnetic signal,the electronic device taps and evaluates at least one reflection signalfrom the emitting device.

In the following designs, the pure determination or, respectively,monitoring of the fill level is expanded to further measuring variables.

Thus, in one design, the electronic device determines, in addition tothe fill level, at least one further piece of information about themedium based on the emitting behavior of the emitting device.

This further information, in one design, is information about aseparating layer between two different phases or substances in themedium of the container.

In an additional or alternative design, the electronic device detectsinformation about a permittivity of the medium.

For example, based on a precise evaluation of at least the reflectedsignal, information is obtained about the medium that is located infront of the emitting device. The permittivity is thereby used in orderto differentiate between different media or in order to determine achange in the medium.

In one design, the presence of different materials is identified basedon the permittivity.

In order to identify the medium using the permittivity, in one design,broadband measurement is carried out, in which the electromagneticsignals are run through a frequency band to determine the resonancefrequency and, thus, the medium.

The medium that was used for carrying out a calibration of the deviceaccording to the invention is also relevant for determining of theadditional information.

In one design, the calibration medium is air.

In an alternative design, the medium that is to be monitored andmeasured is also the calibration medium.

In one design, the phase shift of the complex phasor is evaluated inorder to also identify small changes or differences of thepermittivities.

In one design, contamination of at least one emitting device due toaccumulation of the medium and gradually changing resonance conditionscaused thereby is identified.

Overall, a change of resonance behavior of at least one emitting deviceis determined or identified by the device according to the invention viathe electronic device.

Different individual measured values can be generated and unified intoan overall picture due to the number of emitting devices that areessentially designed in the same manner. Thus, several individualsensors are combined into one multi-sensor.

In one design, each emitting device is individually evaluated.

The following designs ensue:

In one variation, each emitting device is connected to its own signalfeed and its own reflector switch.

In an alternative design, the emitting devices are supplied by a signalsource, however, they each have their own reflector switch.

In an additional design, the emitting devices are supplied by a commonbroadband signal generator. Thereby, however, the lengths of the linesbetween the signal generator and the individual emitting devices differfrom one another such that the reflections occur at times clearlydifferent from one another and allow for assignment to the emittingdevices.

In one design, at least a part of the emitting devices are evaluatedtogether.

It is provided in one design that a support element at least partiallysupports the signal conductor arrangement. At least a part of theemitting devices is attached on or in the support element.

In a further design, all emitting devices are located on or in thesupport element so that the emitting devices can also be mounted attheir operation site via the support element.

The majority of emitting devices on one support element can lead to acoupling of the individual emitting devices. This can result incrosstalk of high frequency signals from neighboring emitting devices.

Thus, for example, de-coupling is required using one of the followingmethods: space-, time-, frequency-, code- and/or polarization divisionmultiplexing.

The invention further relates to a method for determining the fill levelof a medium in a container.

The following description of the method or, respectively, the methodvariations and characteristics can thereby also be implemented usingcorresponding designs of the device described above so that thefollowing implementations also accordingly apply to the device.Conversely, the implementations and examples of the device also applyfor implementation of the method and can be carried out as a method.

The method is initially and essentially wherein several emitting deviceare supplied with electromagnetic signals and that an emitting behaviorof at least a part of the emitting devices is evaluated in view of thefill level of the medium.

The electromagnetic signals in one design are high frequency ormicrowave signals.

The emitting devices can also be seen as individual sensors that arecombined or whose measurement results are combined for determining thefill level or further measuring variables, e.g., in respect to themedium.

The emitting devices, of which there are at least two, are supplied withthe electromagnetic signals for measurement.

In one design, there is a constant supply. In an alternative design, aclocked supply is carried out. Supply is demand driven in one design andin an additional or alternative design, supply depends on whether apredeterminable energy quantum is present.

In one design, the emitting devices are antennae that emitelectromagnetic signals or, respectively, couple the electromagneticsignals in the space in front of the side of the emitting device facingthe medium or the interior of the container.

An emitting behavior of the emitting devices is evaluated for thedetermination of the fill level.

The emitting behavior thereby relates, in one design, to whether aresonance condition has changed for at least one emitting device orwhether it has remained the same.

For example, depending on the design, the resonance frequency, theimpedance, or reflection signals possibly occurring as a result of thesupply with electromagnetic signals are determined or evaluated forassessing the emitting behavior.

If the emitting behavior changes, which is identified, e.g., by a changeof the resonance frequency, then it is assumed that either the medium infront of the emitting device has changed or that the medium has reacheda fill level that is linked to the emitting device. Thereby, thereaching of a fill level quasi also represents a change of the mediumcovering the emitting device, insofar as—for example, when used asoverflow protection—the ambient or process air located in front of theemitting device is replaced by the medium to be monitored.

The emitting devices are, in one variation, designed and arranged sothat they—when reaching a certain fill level—are in contact with themedium.

Due to the—direct or indirect—contact between emitting device andmedium, in particular the emitting behavior of the emitting deviceschanges so that it can be assumed from the identification of the changedemitting behavior that the assigned fill level has been reached.

The use of several emitting devices has, in particular, the advantagethat several fill levels can be identified and/or that at least one filllevel can be redundantly monitored.

Thus, in one design, the behavior of at least a few emitting devices areseparately evaluated.

In one design, all present emitting devices are separately evaluated inrespect to their respective emitting behavior.

The individual data or results for the individual emitting devices aspartial information are subsequently consolidated into an overallstatement.

For this, the emitting devices are summarized into groups in one design,which are each evaluated or monitored in combination.

Plausibility considerations are incorporated in one design.

The individual results for the self-monitoring of emitting devices areused in a further design.

The emitting devices are arranged, at least in part, at different levelsalong a longitudinal axis of the container, in one design.

This arrangement is generated, in one design, by selective positioningof the emitting devices at predetermined levels or with predeterminedlevel differences.

In a further design, the different arrangements result randomly due toassembly, in that, e.g., a support element with the emitting devices ismounted in the container.

Assembly occurs, in one design, at least in part, in a step in which asupport element is screwed into a wall of the container.

Because the object is the detection of fill levels, the emitting devicesare preferably designed and arranged in relation to the containercontaining the medium so that they can interact with the medium on theside of the container.

In one design, at least a portion of the emitting devices is suppliedwith a mono-frequency signal.

In one design, the emitting devices are supplied with the same signaleither simultaneously or time delayed.

Thereby, in one design, the frequency of the signal is the same as theresonance frequency when there is no medium or, in particular onlyambient air located in front of the emitting device that is suppliedwith the electromagnetic signals for determining the emitting behavior.Thus, if the resonance frequency changes, this means that the medium islocated in front of the respective emitting device. In this case, thereaching of a fill level is identified so that, in particular, this isthe implementation of overflow protection.

In an alternative design, the frequency of the electromagnetic signalscorresponds to the resonance frequency in the presence of mediumcoverage. Thus, if, as a result of emitting devices being supplied withsuch signals, the frequency is no longer fitting, it can be assumed thatthe medium has fallen below the assigned fill level, provided that themedium itself does not change in respect to its characteristics relevantfor measurement.

In one design, signals with different frequencies are used—in particularwith different resonance frequencies—in order to determine or monitorthe emitting behavior of the emitting devices concerned in ameasurement, i.e., when the emitting devices are supplied withelectromagnetic signals.

A portion of the emitting devices thus identifies, for example, thetransition from a free to a covered state, while another portion of theemitting devices simultaneously monitors the transition from a coveredstate to one free of medium.

In one design, a portion of the emitting devices is supplied withelectromagnetic signals and signals are tapped by a further portion ofthe emitting devices. The tapped signals thereby result, in one design,from a direct coupling between the emitting devices and, in anadditional or alternative design, result from a coupling via the medium.

In the designs above, signals are respectively used with a specialfrequency that allows for the identification of whether a change hasoccurred or not, i.e., whether the signals and frequency still fit ornot.

In the following design, this yes/no statement is expanded onto a morecomprehensive measurement of the emitting behavior of at least oneemitting device. This allows for more information to be obtained via themedium or via the emitting devices.

It is thus provided in one design that at least a portion of theemitting devices is supplied with several electromagnetic signals havingfrequencies within a predeterminable frequency band.

The designation portion of the emitting devices relates, depending onthe design, to at least one emitting device and at most to all presentemitting devices.

In one design, in particular, a frequency sweep is carried out in orderto measure the resonance behavior of at last one emitting device and,preferably, also to determine the current resonance frequency assignedto the emitting device.

In one design, the permittivity of the medium covering the emittingdevice is deduced based on the determined resonance frequency.

This evaluation is based on the emitting behavior of the emittingdevices being dependent on the material characteristics of thesurrounding substances.

In particular, if the emitting device is understood as an antenna, thenits emitting behavior is dependent on the material characteristics ofthe medium into which the electromagnetic signals are emitted. Thus, ifthere is a known correlation between the emitting behavior and therelevant material characteristic—in this case, permittivity—then thematerial characteristic can be deduced from a measure determined for theemitting behavior.

At least one measure for impedance matching is determined in one designby evaluating the emitting behavior—of at least one emitting device.

At least one measure for impedance matching is determined in one designby evaluating the emitting behavior of several emitting devices.

The emitting devices are understood, for this, to be such that they eachmatch a wave impedance of a line that carries the electromagnetic signalto the wave impedance that is given in the area in front of eachemitting device and thus is also dependent on whether medium is presentor, respectively which medium is present. Thus, a measure for theimpedance matching is determined for fill level monitoring.

A temporal behavior of the measure for impedance matching is determinedand evaluated in one design.

In the above mentioned design, thus, the temporal development of theemitting behavior of at least one emitting device is utilized. Hereby,for example, changes in the medium or changes in the emitting device canbe identified.

If several emitting devices are present, then these are located atdifferent levels in respect to the fill level and the behavior of theemitting devices is separately evaluated. Thus, it is possible toidentify not only the reaching of a fill level, but also even that themedium approaches this fill level.

Such information can be separately issued or can be used purelyinternally for a plausibility check as part of the evaluation.

In the following designs, an approximation function is implemented thatallows for the detection of the medium approaching the fill level beforethe actual reaching of the fill level is signaled.

A limit level switch generally signals one of the two states: “free” or“covered”.

In the case of an approximation function, this is expanded, in onedesign, to the states resulting, e.g., “free”, “approaching”, “covered”and “exceeded”.

These states can correspondingly be transferred on established outputsignals such as e.g., 4 . . . 20 mA signals or control voltages.

It is advantageous for the designs when the emitting devices aredecoupled from one another or when they are operated so that a couplingis essentially avoided.

Thus, in one design, it is detected that the medium is approaching apredeterminable fill level using the emitting behavior of at least twoemitting device, in that the measure for impedance matching isdetermined for the at least two emitting devices and in that thedetermined measure is evaluated in dependence on the point in time ofthe respective change.

If, for example, overflow protection is implemented, then is can beassumed that first a lower fill level is reached before a higher filllevel is reached, insofar as the two emitting devices are assigneddifferent fill levels. This means that, first, the lower emitting deviceindicates the reaching of its associated fill level and that, then, theupper emitting device exhibits emitting behavior that corresponds tobeing covered by medium.

Alternatively, and without taking points of time into consideration, itis only evaluated whether both emitting device display the reaching ofthe respectively associated fill level.

The temporal evaluation is, however, particularly advantageous forcalibration in order to allow a reliable identification of the filllevel without the fixed specification of an orientation of the emittingdevices in relation to the container.

Furthermore, in one design, the temporal evaluation allows forinformation about the speed at which the fill level changes.

It is provided in one design that the emitting behavior of at least twoemitting devices are evaluated in the sense of redundancy.

In one design, thereby, the emitting behavior of the at least twoemitting devices are evaluated in view of a common fill level and/or acommon fill level range.

For the above design, preferably, those emitting devices from thepresent emitting devices are chosen or grouped in respect to evaluation,in which the medium causes a change in the emitting behavior when thesame fill level or a same fill level range is reached.

In one design, at least two emitting devices are evaluated together,e.g., at least in part, the same components or switch elements are used.

In an alternative design, the emitting behavior of the emitting devicesis separately detected and evaluation data is summarized orsynchronized.

The evaluation of data from the emitting devices as fusion of theindividual measurements possible with the emitting devices is dependenton whether the emitting devices relate to the same or different filllevels of the medium.

The arrangement between emitting device and fill level is therebyindependent of the arrangement of the emitting devices—e.g., on onesupport element—relative to one another and is dependent on the type ofattachment of the emitting devices in relation to or in the container,in which the medium is located.

In order for the assembly of the emitting devices in the container toenable a greater amount of freedom and independence, it is provided inone design that there is no fixed configuration for which emittingdevice, either together or separately, the emitting behavior isevaluated.

This means that only after the attachment of the emitting devices is itdetermined by which emitting devices the emitting behavior is evaluated,either together or separately. Thus, only after assembly is itdetermined which emitting devices relate to different fill levels orfill level ranges and which relate to same fill levels or fill levelranges.

A fixed specification would mean that the emitting devices have to beattached in the container according to a specification. This is avoidedor not necessary due to the above mentioned design.

Calibration of the mounted measuring arrangement is advantageous for theflexibility of assembly, which is designed, for example, like thefollowing variations.

In one design, calibration is carried out in that a temporal sequence ofa change in the emitting behavior is determined for individual emittingdevices.

Preferably, the calibration is not carried out for a selected change ofthe fill level of the medium, but rather results from the change of thefill level of the medium related to the process. The measuring device isthus attached at the measuring site and immediately put into operation,wherein calibration for future use results from the first determinationof the fill level. Calibration includes, in particular, the assignmentof the emitting devices to a respective fill level.

If, for example, the reaching of a fill level is used for overflowprotection, then, based on the temporal sequences of the changes in therespective emitting behaviors or based on a simultaneity of the changes,it is concluded how the respective assigned fill levels are arranged toone another or how they coincide.

Preferably, this occurs during the normal and process-dependent reachingof the respective fill level.

In one design, a “configuration mode” is started after mounting ameasuring device for implementing the method and preferably before afirst filling event, in that the emitting devices are individuallyoperated and, in particular, the respectively occurring measuringresults are separately processed.

In one design, a central emitting device is present, wherein themeasuring results of the other emitting devices are evaluated in respectto the central emitting device.

In one design, the remaining emitting devices are symmetrically arrangedaround the central emitting device. This allows for the alignment of thefill level senor to be more precisely determined.

In one design, the other emitting devices are grouped into groups andfill levels above and below the central emitting device are assignedbased on the signaling of the central emitting device being covered.

Additionally, in a further design, a logical link within the group iscarried out for redundancy configuration.

In a design without a central emitting device, grouping is carried outwhen half of the emitting devices signal coverage.

Additionally or alternatively, the evaluation of the emitting behavioror the further processing of the correspondingly determined value ormeasure numbers for at least a portion of the emitting devices aretaught in a learning mode.

In the learning mode, the respective emitting behavior of the consideredportion of the emitting devices is separately evaluated. Then, based onthe emitting behavior of at least one chosen emitting device, anevaluation of the emitting behavior of the other emitting devices iscarried out.

If, due to the arrangement of the emitting devices relative to oneanother and as a result of assembly, it is known that three differentfill levels can be monitored, then the emitting behavior of the emittingdevice that is assigned the middle fill level is particularly evaluated,insofar as a middle fill level is defined by this emitting device.

If idle state protection is constituted by the device or the method,then it can be assumed that after assembly of the emitting devices, orthe support element, or the device for creating a measuring arrangementwith the container and the device, the medium is filled into thecontainer and also exceeds the emitting devices. Calibration can thus becarried out during this first filling, wherein, however, the evaluationor assessment of the individual results for the running measuringoperation is different than the overflow protection mode.

The following designs relate to the assembly of emitting devices.Thereby, the orientation of the emitting devices results randomly or, inone design, is deliberately implemented.

In one design, the emitting devices are attached in the container inrelation to one another so that at least two emitting devices are eachassigned different fill levels of the medium.

The assignment of fill level to emitting device thereby results in thatthe medium causes a change in the emitting behavior of the emittingdevice assigned the fill level when reaching the respective fill level.

In this design, the mounted emitting devices are located at differentlevels of the container so that they each monitor different fill levelsor make the reaching of these fill levels able to be signalized.

In one design, the monitoring of several fill levels is expanded in thatthe emitting devices are attached in relation to the container so thatat least three emitting devices are each assigned different fill levelsof the medium.

Here, the mentioned assignment is also given in that the medium causes achange in the emitting behavior of the emitting device assigned the filllevel when reaching the respective fill level.

The middle fill level is, in one design, defined as the actual filllevel to be monitored and undergoes a special evaluation.

The reaching of the fill level above or below the middle fill level thenmeans that the medium is approaching the relevant fill level or that therelevant fill level has already been exceeded (in overflow protection)or fallen below (in idle state protection). Thus, in this design, a sortof advance warning and an ultimate overflow or idle state signalizationare possible.

In an additional or alternative design, the emitting devices areattached in relation to the container so that at least two emittingdevices are each assigned an essentially same fill level or same filllevel range of the medium.

For the lot of emitting devices, in this design, a position results inwhich at least two of the present emitting devices relate to the samefill level or the same fill level range.

The magnitude or extent of the fill level range can thereby be suitablydefined by the user, e.g., depending on the desired resolution of filllevel detection.

The assignment of fill level or fill level range to emitting device isalso given here in that the medium causes a change of the emittingbehavior of the at least two emitting devices assigned the fill level orfill level range when reaching the fill level or fill level range.

Whether the same fill level is monitored—in the scope of a predeterminedtolerance—depends on the geometry of the emitting devices and also onthe orientation of the emitting devices in relation to the longitudinalaxis of the container that runs along the fill level.

Whether a range is monitored, is additionally dependent on thespecification of the local resolution to possibly be set by the user.

If several emitting devices relate to the same fill level or to the samefill level range, then redundancy is given. This can be used for thereliability of the signal for reaching the fill level or this can beused for identifying, e.g., an aging process or error in the individualemitting devices.

An advantage of redundancy is always that, even when an emitting devicefails, measurement with the remaining emitting devices of the same groupis further reliably possible.

The following additional or alternative designs relate to monitoring.

It is thereby provided that information about the state of the emittingdevice is detected from a temporal change of the emitting behavior of atleast one emitting device.

Using the temporal development of the emitting behavior, e.g., with agradual change in the resonance frequency or with a broadening of theresonance curve, etc., it can be identified how the emitting devicedevelops (e.g., as a result of aging) or what happens to the emittingdevice (e.g., as a result of sedimentation).

In a design associated therewith, the determined information is used fordetermining the fill level of the medium.

A corresponding recalibration takes place in one design based on thedevelopment of the emitting device.

Such a recalibration is carried out, for example, in one design asfollows:

A sedimentation of the medium on an emitting device possibly only leadsto a shift of the resonance frequency of the concerned emitting deviceand does not prevent the detection of the change between the free andcovered states. However, the concept leads to the frequency having to betracked, relative to which a change is coverage is identified.

This tracking is carried out in that the measuring results within agroup of emitting devices that relate to a same fill level or fill levelrange are compared to one another and that an adaptation duringprocessing of the emitting device is carried out, wherein the result ofwhich does not correspond to the other results.

In one design, an emitting device is not longer used for measurementbased on the determined state of the emitting device.

The information about the state of the emitting device relates to adegree of contamination or aging of the considered emitting device, inone design.

In the following designs, in addition to the detection of the fill levelwith the emitting devices, at least one characteristic of the medium isdetected in addition to the fill level.

Thus, it is provided in one design that the emitting behavior of atleast one emitting device is evaluated in view of at least onecharacteristic of the medium.

In one variation for the above design, reference is made to the emittingbehavior of the emitting devices depending on which permittivity themedium covering the considered emitting device exhibits.

Thus, if the fill level doesn't change, but the emitting behavior doeschange, then a change in the permittivity can be deduced.

Alternatively, in a known correlation, e.g., using correspondinglystored data or functions, a value for the permittivity is determinedfrom the determined resonance frequency.

That the fill level has not changed, can, e.g., be determined in thatthe emitting behavior of the emitting devices assigned other fill levelsor the same fill level is evaluated.

Thus, in one design, information about the permittivity of the medium isdetermined based on a resonance frequency of at least one emittingdevice.

A particular use, in which the invention can be implemented very well,is formed of the medium composed of more than one substance.

If different substances that don't mix are located in one container, aseparating layer is the usual result.

If the substances that together form the medium in the container differ,then in one design, the presence of a separating layer is identified anddata is determined for the separating layer.

In one design, different emitting devices obtain information about thepresence of a separating layer in the medium due to the presence ofdifferent resonance frequencies.

Thus, if the result for several emitting devices is that the mediumcovers each of the emitting devices, then the resonance frequencies—ascharacteristic for emitting behavior—are so different that thepermittivities of the substances covering the emitting devices differand it can be concluded that a separating layer is present or that atleast two different substances or phases are present.

In respect to the separating layer, the level of the separating layer isdetermined in the following design. For this, at least the followingsteps are provided:

Based on the emitting behavior of at least two emitting devices, towhich different fill levels are assigned, the reaching of the fill levelby the medium—of several substances or phases or general states (e.g.,liquid and foam)—is determined.

Then, a first duration between the reaching the respective fill levelsis determined, i.e., the duration between the points in time at whichthe fill level is reached. A filling speed is determined from the firstduration and a known fill level distance—i.e., different inheight—between two fill levels assigned to two emitting devices.

Finally, a second duration for one of the two emitting devices isdetermined that lies between the reaching of the fill level assigned tothe emitting device and a change in the resonance frequency of theemitting device.

If the emitting device is covered by the medium for the first time, thenthe medium with the upper substance of the two substances reaches theassociated fill level. If the resonance frequency changes, this meansthat the emitting device is covered by the next substance. Thus, thesecond duration indicates how long the upper substance has moved overthe emitting device.

Thus, the invention also relates to a device with a signal conductorarrangement for identifying a separating layer or for detecting dataabout a separating layer.

In detail there is a plurality of possibilities for designing andfurther developing the invention. Reference is made, on the one hand, tothe patent claims subordinate to patent claim 1 and, on the other hand,to the following description of embodiments in conjunction with thedrawing. The drawing shows

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a part of a processing system

FIG. 2 is a top view of a part of a schematically represented signalconductor arrangement of a device for fill level measurement in a firstdesign,

FIG. 3 is a top view of a signal conductor arrangement in a seconddesign,

FIG. 4 is a cross section through a schematic design of a signalconductor arrangement in a third variation,

FIG. 5 is a schematic cross section through the device for fill leveldetermination in use in a processing system,

FIG. 6 is a schematic representation of a first design of a part of anelectronics unit,

FIG. 7 is a schematic representation of a second design of a part of anelectronics unit,

FIG. 8 is a schematic representation of a third design of a part of anelectronics unit,

FIG. 9 is a schematic representation of a fourth design of a part of anelectronics unit,

FIG. 10 shows top views of eight different signal conductorarrangements,

FIG. 11 is a schematic representation of the processing of the emittingdevices of a device according to the invention,

FIG. 12 is a schematic representation of the detection of data via aseparation layer with the aid of a device according to the invention,

FIG. 13 is a flow chart for the start-up of a device according to theinvention,

FIG. 14 is a schematic flow chart of the self-monitoring of a deviceaccording to the invention and

FIG. 15 is a schematic flow chart in respect to the evaluation of thebehavior of an emitting device.

DETAILED DESCRIPTION OF THE INVENTION

It is schematically represented in FIG. 1 how the fill level of a medium2 in a container 3 is monitored by a device 1 according to the inventionin a processing system.

The device 1 is used here, in particular, as overflow protection.Accordingly, the device 1 can, however, also be used here as idle stateprotection—not shown here.

The device 1 in the shown schematic design has an electronic device 4and a signal conductor arrangement 5. The electronic device 4 generateselectromagnetic signals—preferably via a signal source, not shownhere—that are supplied to the signal conductor arrangement 5.

After supplying the signals, the electronics unit 4 evaluates thebehavior of the signal conductor arrangement 5 or, respectively, theindividual components to be described in the following in terms ofwhether or not the medium 2 is in contact with the signal conductorarrangement 5.

In the case of overflow protection, the change from uncovered to coveredstate is detected. Conversely, in the case of idle state protection—notshown here—, it is signalized when the signal conductor arrangement 5 isfree of medium.

The dependence of the resonance behavior—and in particular the resonancefrequency—of the signal conductor arrangement 5 or its components on thesurroundings of the signal conductor arrangement 5 is utilized whenmeasuring or monitoring the fill level.

In particular, that the resonance behavior is dependent on whether thepresence of coverage is from a medium 2 or from ambient air is utilized.

The signal conductor arrangement 5 extends into the wall 14 of thecontainer 3 and is thus a part of the side wall. For this, the wall 14has a recess that is sealingly closed again by the signal conductorarrangement 5.

FIG. 2 shows a top view of the signal conductor arrangement 5 and itsoverall six emitting devices 6.

The emitting devices 6 are arranged in a common support element 7.Thereby, this is a ceramic substrate, in or onto which the emittingdevices 6 are created. The support element 7, here, is disk-shapedhaving a circular circumference.

The emitting devices 6 are designed circularly in the shown embodimentand are located along a longitudinal axis 8 at three different levels.

In alternative embodiments—not shown here—not all emitting devices havethe same shape or the emitting devices are, e.g., oval or rectangular.

The emitting devices are arranged mirror symmetrically to thelongitudinal axis 8 in the shown embodiment and can be separated, here,into three groups—given by three levels.

Three emitting devices 6 (here shown at the bottom) are thereby atlevels slightly staggered to one another and together monitor a broaderstrip of the fill level—in the mounted state and under the conditionthat the longitudinal axis of the support element and the longitudinalaxis of the container essentially coincide.

The two outer of the three lower emitting devices 6 are, in turn,located at the same level, so that a redundancy also results especiallyfor monitoring the assigned fill level within this strip.

In the next level, an individual emitting device 6—arranged in themiddle here—borders thereon, to which two emitting devices 6 connect.

The two upper emitting devices 6 provide redundancy for the assignedfill level, since they are both located at the same level.

Overall, three different fill levels or fill level ranges results thatare to be monitored by the individual emitting devices 6. Plausibilityconsiderations can be made using the measuring results at the differentlevels in order to increase the reliability of fill level determinationor monitoring.

The resolution, with which the reaching or falling below of a fill levelcan be detected, is increased with the number of different levels of theemitting devices—depending on use and evaluation.

For insertion, an outer thread 13 is provided on the outer surface ofthe circular support element 7. Accordingly, the wall, into which thedevice 1 is to be mounted, has an inner thread so that the supportelement 7 can be screwed into the wall and closes it again.

Different end positions of the emitting devices 6 of the signalconductor arrangement 5 result from screwing as means of attachment.

In order to be able to react to this diversity of orientations inrelation to each fill level to be monitored due to mounting, the type ofevaluation of the emitting devices 6 is not rigidly specified, ratherthe evaluation or interpretation of the measuring results of theindividual emitting devices 6 are each adapted to the use or to the endposition.

A further design of the emitting devices 6 on the support element 7 isshown in FIG. 3.

In the shown exemplary embodiment, eight emitting devices 6 arerotation-symmetrically arranged around one, single emitting device 6located in the center.

It can be seen that this number and distribution of emitting devices 6allows an arbitrary number—created by turning—of end positions of thesupport element 7, which are each used for monitoring the same or verysimilar fill levels.

Thereby, depending on the measuring accuracy that can be implementedwith the emitting devices 6, significantly more differing levels canpossibly also be defined—here, along the longitudinal axis 8 of thesupport element 7. In the case of greater spread or lower resolution,the measuring sections can also coincide.

Metal strips are implied between the emitting devices 6 that cause adecoupling of the individual emitting devices 6.

Additionally, three lines for electronic connection are implied behindthe support element 7.

A third variation of the signal conductor arrangement 5 is seen in FIG.4.

It can be seen in the cross section that the support element 7 is amulti-layer ceramic (being striped in the one case and empty in another,for clarity) having, here, three emitting devices 6 inserted between itslayers.

The emitting devices 6 are thereby protected against medium—not shownhere—by the support element 7, itself, and also by the protective layer10.

In the illustrated embodiment, the support element 7 is surrounded by astructure on the side that also bears the outer threading 13 forscrewing and attaching into the recess—not shown here—in the wall of thecontainer.

It can be seen in FIG. 5 that two emitting devices 6 as parts of thesignal conductor arrangement 5 of the device 1 are arranged within thesupport element 7 at different levels along the longitudinal axis 9 ofthe container 3. The container 3 thereby has a corresponding recess thatreceives the support element 7.

The emitting devices 6 are protected by a dielectric protective layer 10facing the medium 2, which here are mounted flush with the inner side ofthe container 3 that contains the medium 2.

The electronic device 4 has a measuring device 12 and two reflectorswitches 11 that are each assigned to an emitting device 6.

The measuring device 12 generates electromagnetic signals that are givento the emitting devices 6 via the two reflector switches 11.

The reflector switches 11 receive a reflection signal as response signalfrom their respective emitting devices 6, from which a measure for theresonance conditions of each emitting device 6 results.

This information of the reflector switches 11 is transmitted to themeasuring device 12 for further processing. the reflector switches 11thus represent a sort of preprocessing in the shown design.

Based on the data of the reflector switches 11 it is determined in themeasuring device 12 whether the medium 2 covers one of the emittingdevices 6.

Then, the reliability of the individual measurement is examined based onthe data of all emitting devices 6.

Finally, the measuring device 12 generates at least one switch signalthat, here, represents the reaching of a fill level.

Additionally or alternatively, the falling below of a fill level issignalized or, respectively, information about the rising or falling ofthe fill level is issued. This is possible in that the emitting devices6 are located at different levels along the longitudinal axis 9 of thecontainer 3, so that at least two fill levels can be monitored.

Exemplary embodiments of components of the electronic device 4 forimplementing measurement or monitoring of the fill level are shown inthe illustrations in FIGS. 6-9.

Thereby, only one emitting device 6 that is additionally designed as anantenna is shown in each. The shown embodiments are thus possibly to becombined with several emitting devices 6 or each emitting device 6 hasone of its own of the electronic switches shown.

Narrow band scalar measurement is implemented as an example in FIG. 6.

The emitting device 6 is continuously supplied with a mono-frequencysignal during narrow band scalar measurement.

The supply frequency f₀, i.e., the frequency of the electromagneticsignal, is chosen in one embodiment so that it corresponds to theresonance frequency of the emitting device 6 in the case that only airand, in particular, no medium to be detected is located in front ofemitting device 6.

Thus, if the emitting device 6 is supplied with the signals and nomedium is located in front of the emitting device 6, then the emittingdevice 6 emits the electromagnetic signals.

With the aid of the reflector switch 11, the adaptation of the emittingdevice 6 at the supply frequency f₀ is permanently monitored.

The signal generator 15 permanently supplies the emitting device 6 withthe signal of the frequency f₀.

The reflector switch 11 issues a DC voltage that depends on the ratiobetween the power of the signals of the signal generator 15 and thepower reflected at the emitting device 6.

Additionally, a low-pass is provided in the reflector switch 11, here.

In a downstream comparator 16, the DC voltage U1 is compared to anexternally applied reference voltage U2 and evaluated with it.

If air is located in front of the emitting device 6, then the emittingdevice 6 is adapted and its input reflection is small. The reflectometervoltage U1 is, in this case, less than the reference voltage U2, so thatthe comparator 16 issues a low level as voltage U3.

If a medium that is not air is located in front of the emitting device6, the resonance frequency of the emitting device 6 is shifted anddiffers, in particular, from the frequency f₀ of the electromagneticsignals. The emitting device 6 thus has a bad adapting behavior at theapplied frequency f₀.

Hereby, a higher input reflection of the emitting device 6 results, sothat the DC voltage U1 of the reflector switch 11 also increases.

If the reflector voltage U1 is greater than the reference voltage U2,then the comparator 16, which is formed essentially of a differentialamplifier that, here, generates a high level that signalizes thereaching of the fill level associated with the emitting device 6.

This means that the downstream evaluation unit—not shown here—onlyevaluates the voltage U3 or needs to identify the possibly occurringchange in voltage in order to evaluate the emitting behavior of theemitting device 6 for the use as level limit switch.

FIG. 7 shows an arrangement for implementing a narrow band phasormeasurement.

This embodiment is advantageous, in particular, when the emitting device6 is covered with a protective layer—not shown here—or when the mediumto be detected has a very low permittivity.

For this, the narrow band scalar measurement shown in FIG. 6 is expandedby a further measuring point to a complex measuring reflector switch—ora so-called IQ reflectometer.

The essential change, as opposed to the embodiment of FIG. 6, isexperienced by the reflector switch 11.

Both the signal generated by the signal generator 15 as well as thereflection signal coming from the emitting device 6 are separated andsupplied to a second measuring site for the second measuring site.

In one of the two signal paths, there is a 90° phase shifter.

The first, unchanged measuring site delivers the “in-phase” signal Uiand the second measuring site connected to the phase shifter deliversthe “quadrature” signal Uq.

Both signals Ui and Uq are digitized in the measuring device 12 and arefurther processed in a microprocessor in the shown embodiment.

With the aid of the implemented IQ measuring site, a phase evaluation ofthe reflected signal can be carried out. It is thereby advantageous thatthe phase shift that is created by the reflection on the fill level is avery sensitive measure.

FIG. 8 deals with a broadband scalar measurement.

In the case that the medium to be detected has high losses, theadaptation curve of the emitting device is broadened over the frequency.

This can have the result that, when the emitting device 6 is covered bythe medium, insufficient reflection can be detected.

For this, a broadband adaptation curve of the emitting device 6 isrecorded with the shown embodiment.

The signal generator 15 generates electromagnetic signals for thishaving different frequencies between two limiting frequencies fmin andfmax.

This occurs, for example, using a PLL (phase locked loop) operated VCO(voltage controlled oscillator). Alternatively, a direct digitalsynthesis (DSS) is implemented.

The frequency of the signals is set by a microprocessor in the shownexample, which is a part of the measuring device 12 here.

The reflectometer voltage U1 is directly digitized via a analog-digitalconverter in the shown and exemplary embodiment, so that the respectivereflection value of the set frequency of the electromagnetic signals ofthe signal generator 15 can be assigned.

After a complete frequency sweep, the adaptation curve is evaluated inthe measuring device 12, wherein the lowest reflectometer voltage U1determines the resonance frequency of the emitting device 6.

If the resonance frequency deviates from the frequency that is assignedto the non-covered state, then the reaching of the fill level assignedto the emitting device 6 is signalized.

A broadband phasor measurement can be seen in FIG. 9.

The reflector switch 11 is unchanged to that of the embodiment in FIG. 6and also generates an “in-phase” signal Ui and a “quadrature” signal Uq.

The signal generator 15 is designed identical to the one in FIG. 8. Theelectromagnetic signals thus also have different frequencies, whereinthe control of the frequency also occurs here with a microprocessor aspart of the measuring device 12.

This switch is, in particular, advantageous for the case that a thinprotection layer is located in front of the emitting device 6 and,insofar as the influence of the medium on the reflection characteristicis potentially reduced by the protective layer.

The switch is even more advantageous when the medium is additionallystrongly lossy. Thus, the combination of phasor evaluation and broadbanddetection particularly lends itself to this case.

Eight different top views of the side of the signal conductorarrangement 5 which will face the medium in the device according to theinvention are shown in FIG. 10.

The longitudinal axis 9 of the container—not shown here—into which thedevice is inserted is depicted so that it can be identified that themedium will increase from bottom to top.

Embodiments or orientations in relation to the longitudinal axis 9 arelocated in the upper of the two shown rows, which allow for thedetection of two different fill levels. the four embodiments in thelower row allow for the monitoring of three fill levels.

It can be seen that there are four different arrangements of theemitting device 6 on the support element 7, each being present in twodifferent orientations in relation to the longitudinal axis 9. Thismakes clear the effects of rotary mounting of the signal conductorarrangement 5.

Pairs belonging together are located in the upper and lower rows, eachat a first and second position (from the left side). Additionally, theembodiments at the second to last position in the upper and lastposition of the lower row as well as at the last position of the upperand second to last position of the lower row belong together.

Clearly, a partially different measuring geometry in relation to thecontainer or especially to its longitudinal axis 9, along which themedium increases or decreases, results due to the screwing in of thesupport element 7 during assembly.

This effect is particularly clear in the variations at the second tolast and last position: Depending on the angle of rotation, two or threefill levels or can be detected with the same geometry of the emittingdevices 6.

In the orientation of the emitting devices 6 in relation to the supportelement 7, in which the emitting devices are arranged each on a diameterof the circular support element 7 (embodiments at first and secondposition of the two rows), as many fill levels can be detected as thereare emitting devices 6. Here, this is two or three fill levels.

An exception then results when all emitting devices 6 are arrangedperpendicular to the longitudinal axis 8 of the container. In this case,—not shown here—, only one fill level can be monitored, however, ascompensation with a correspondingly high redundancy.

The arrangement of the emitting devices 6 in a square for four emittingdevices 6 or in the form of a capital V for three emitting devicesallows for the monitoring of different amounts of fill levels dependingon the rotation or for the redundant monitoring of a fill level or filllevel range depending on the rotation.

The dependence of possible measuring levels or the fill levels to bemonitored makes the advantage clear, which then results when the type ofevaluation of the emitting behavior of the emitting devices 6 is notstrictly specified, rather is configured after assembly at the operationsite and thus is adapted to the prevailing conditions.

A variation is shown purely schematically in FIG. 11, how nine emittingdevices 6 on a support element 7 are evaluated together by an impliedmeasuring device 12.

For clarity, all elements and components are left away that are used forthe actual detection of the emitting behavior of the emitting devices 6,so that, here, the emitting devices 6 are directly joined to thecomponents of the measuring device 12 in the schematic sketch.

In the following case, it is observed that the device is used foroverflow protection and that the fill level of the medium increases frombottom to top in the drawing level.

Furthermore, the emitting devices 6 each then directly generate a signalwhen they are covered by the medium.

Eight of the nine emitting devices 6 are arranged radially around thecircumference on the support element 7. The ninth emitting device 6 islocated in the center, around which the other emitting devices 6 areaccordingly rotation symmetrically distributed. Overall, three emittingdevices 6 lie on one diameter of the support element 7.

It can thereby be identified that the symmetrical distribution of theemitting devices 6 on the support element 7 and their increasednumber—in relation to, e.g., the embodiments of FIG. 10—allow for aplurality of different mounting situations, i.e., allow for differentend positions after rotation, which essentially lead to the samemeasuring geometry.

The arrangement of the emitting devices 6 in relation to the containerand thus also in relation to the possible fill levels of the medium isunderstood as measurement geometry.

The nine emitting devices 6 are grouped into three groups that eachrelate to one fill level or fill level range.

The three middle emitting devices 6 are located at one level and arethus used for monitoring a fill level.

The three upper and the three lower emitting devices 6 are each slightlyshifted in height in respect to one another, wherein each of the twoouter emitting devices 6 are located at the same level and the middleemitting device 6 is located at a position either higher or lower thanits neighbor.

In that each of the three emitting devices 6 of the groups are connectedto one another or are evaluated together, the three upper or the threelower emitting devices 6 together monitor a fill level range, i.e., aspatial area that is determined by the geometry of the individualemitting devices 6 and their relative distribution.

In the shown embodiment, two each of the emitting devices 6 of thegroups are connected to one another by a logical “AND” element 17. Thismeans that this “AND” element 17 supplies a logical “one” when bothemitting devices 6 generate the same signal.

Thus, if both emitting devices 6 signalize that they are covered by themedium in that this is derived from the respective emitting behavior,e.g., from the resonance frequency, then the assigned “AND” element 17issues a “one”.

Thus, with the “AND” element 17, it is monitored whether two emittingdevices 6 generate the same signal. Thus, the three emitting devices 6in one group are connected to one another in terms of redundancy.

An “OR” element 18 is subordinate to the three “AND” elements 17 pergroup, which generates a signal when at least one of the three “AND”elements 17 issues a positive signal.

The “OR” elements 18 thus combine the individual signals of the emittingdevices 6 into one group signal.

The “OR” elements 18, in turn, follow the “AND” elements 19 that connectthe group signals of the lower and the middle group or the middle andthe upper group to one another in order to control the three signalunits 20 that act as a sort of traffic light here.

In the following, a possible order of events is observed for the use asoverflow protection.

At the beginning, the medium—not shown here—is, for example, stilllocated below all of the emitting devices 6.

The medium increases and reaches the lowest emitting device 6, whichgenerates a corresponding signal.

However, this is only a signal for the reaching of the fill level rangewithin the lower group, thus no signal is given to the outside thatindicates coverage. This is prevented by the two “AND” elements 17accordingly assigned to the emitting device 6.

If the medium continues to increase, then it also reaches the two outeremitting devices 6 of the lower group.

Since, thereby, all three emitting devices 6 signalize coverage, thesignal for reaching the fill level range results for the lower group andthe lower “OR” element 18 can directly actuate the lower signal unit 20connected to it.

If the fill level of the medium continues to increase, then all threeemitting devices 6 of the middle group, which are all arranged at thesame level, are covered. Thus, all three generate the signal that thefill level has been reached. The “AND” elements 17 pass this informationfurther via the “OR” element 18 to the subsequent “AND” element 19.

The signal of the middle group and the signal of the lower group areconnected to one another via the “AND” signal 19.

Thus, the result of the middle group is checked in respect toplausibility.

The middle signal unit 20 can then only display the reaching of themiddle fill level when the lower fill level has also been reached or issubsequently exceeded.

If the fill level continues to increase, then the medium reaches the twoouter emitting devices 6 of the upper group, which are connected to oneanother by the lower “AND” element 17 of the three upper “AND” elements17. Thus, the upper group already generates a signal at this fill level,which then can actuate the upper signal unit 20 in conjunction with thesignal of the middle group.

Thus, if the medium is found in the fill level range of the upper group,then all three signal units 20 are lit up.

The components of the measuring device 12 shown here for processing theindividual results in respect to the emitting behavior of the emittingdevices 6 are designed, as an example, as logic components.

The implementation thereby occurs, in an alternative embodiment, in theform of at least one microprocessor and, in an additional embodiment, inthe form of at least one FPGA (field programmable gate array).

It is shown in FIG. 12, how the location of a separating layer 21 isidentified and detected with the device according to the invention.

Separating layers result when the medium is made up of two substances orphases that do not mix. For example, a medium consisting of oil andwater is possible.

One side of a container 3 is shown purely schematically, in whose—hereback—wall a support element 7 having two emitting devices 6 is located.

Additionally shown, is the medium 2 in front of the container wall,which is formed of substances having a separating layer 21 locatedbetween them.

In the shown situation, the upper substance already covers the loweremitting device 6 and approaches the upper emitting device 6.

If the medium 2 continues to increase, then the lower emitting device 6is, at a certain point in time, no longer covered by the uppersubstance, but rather the lower substance

If the two substances of the medium 2 differ in view of theirpermittivity, then the change at covering of the lower emitting device 6leads to a change in the emitting behavior, in particular a change inthe resonance frequency.

At a further point in time, the upper substance reaches the upperemitting device 6, which is then not longer free and uncovered, ratheris covered, so that its emitting behavior also changes.

Two further time durations are necessary for determined data about theseparating layer 21:

This includes a first duration that is found between the points in timeat which the emitting devices 6 signalize the change from uncovered,i.e., free, state to a covered state. These are thus the points in timeat which the upper substance reaches each of the emitting devices 6.

In combination with the level difference between the two emittingdevices 6, the first duration allows for the determination of theincreasing or filling speed of the medium 2.

Thereby, the speed at which the medium 2 increases can be determined.

It is assumed, here, that the fill level of the medium 2 increasesuniformly and that, e.g., that there are no pauses or that the filllevel decreases in the meanwhile.

Furthermore, a second duration is also necessary that is located betweenthe points in time, at which a first coverage by the medium or thechange of substances is determined by an emitting device.

The second duration is a measure for how fast the upper substance of thetwo substances extends beyond the assigned emitting device.

Steps for start-up of a device according to the invention and, inparticular, for free configuration of the evaluation are shown in FIG.13.

The device—not shown here—thereby has, as an example, five emittingdevices, whose orientation relative to the longitudinal axis of thecontainer is not known as a result of the rotary assembly and would bevery difficult to determine since the emitting devices are located inthe direction of the container interior.

In step 100, the device is mounted at the measuring site in that thesupport element is screwed into a recess of the container wall.

Depending on the desired end position, the emitting devices are arrangeddifferently to the container or, in particular, to its longitudinal axisand thus relate to different or same fill levels in an unpredictablemanner.

In step 101, normal measuring operation is started, without a fill levelto be monitored being deliberately approached and only for calibration.

In step 102, the medium reaches an emitting device of the deviceaccording to the invention for the first tie—only as an example here—andcovers it, so that the emitting behavior of this emitting device changesnoticeably.

This emitting device is thus assigned the lowest fill level in step 103.

In step 104, the medium reaches two other emitting devices that bothaccordingly signalize that coverage has occurred.

In step 105, it is checked when the lower emitting device is stillcovered.

In step 106, the information from the lowest emitting device is combinedwith signals of the two higher emitting devices so that both emittingdevices are assigned a common fill level and that both are coupled toone another in the sense of redundancy. Further, the assignment of filllevel to emitting devices is carried out.

In step 107, the fill level further increases and reaches two additionalemitting devices.

In step 108, it is concluded from the points in time, at which the twolast-mentioned emitting devices signalized contact to the medium, thatthere is a slight level difference between the two, since there is atime difference between the signals.

In step 109, the two emitting devices are assigned to one group despitethe difference and thus also to one fill level range and not to anarrower fill level.

In step 110, the signals from all emitting devices are compared to oneanother again and calibration is finalized, after the resonancefrequencies determined by the individual emitting devices in the case ofcoverage have been determined and reset.

FIG. 14 shows several steps for identifying a contamination of—not shownhere—emitting devices.

In step 200, the resonance frequency is measured in the covered state ofan emitting device.

In step 201, a new measurement of the resonance frequency of theemitting device occurs for self-monitoring after a given duration, forwhich it is necessary that the covered state exists. For example, themeasuring signals of the remaining emitting devices are used for this.

In step 202, the current frequency value is compared to the storedvalue.

If the values are located within a tolerance range, then there is areturn to step 201 and the frequency measurement is repeated at thegiven time.

However, if there is a deviation beyond the tolerance range, then it isshown in step 203 that the emitting device is no longer in a correctstate and, in particular, is contaminated.

FIG. 15 shows a general course for the processing of the emittingbehavior of an emitting device.

A measure for the emitting behavior of the emitting device is determinedin step 300. This is, for example, the resonance frequency.

In step 301, this measure is compared to a stored value and it isdetermined whether a change exists.

If there is no change, step 300 begins again.

In the case of a change, it is checked in step 302, whether the chosenemitting device is to be considered together with further emittingdevices in the sense of redundancy.

If this is not the case, a plausibility check is carried out in step303.

For example, it is checked, whether the result resulting from the changein emitting behavior of the chosen emitting device agrees with theinformation of the other emitting devices. If, e.g., the change from“uncovered” to “covered” results, then the emitting devices assignedlower fill levels have to report coverage.

If this plausibility is fulfilled, then it is signalized in step 304that the fill level of the medium associated with the emitting devicehas been reached.

However, if there are discrepancies, an error message occurs in step305.

If it is seen in step 302, that there are further emitting devices thatare assigned the same fill level or fill level range, then acorresponding comparison is carried out in step 306.

If the redundancy check in step 306 shows that the state signalized bythe change in the emitting behavior of the emitting device agrees withthat of the other emitting devices connected to one another byredundancy, then the plausibility check is carried out in step 303.

However, if there are differences, then an error message is alsogenerated in step 305 in the shown embodiment.

Step 304 then finally followed again by step 300.

What is claimed is:
 1. A device for determining the fill level of a medium in a container, comprising: at least one electronic device and at least one signal conductor arrangement, wherein the electronic device supplies the at least one signal conductor arrangement with electromagnetic signals, wherein the signal conductor arrangement has a plurality emitting devices for emitting the electromagnetic signals, wherein a support element at least partially supports the signal conductor arrangement, and wherein the support element is insertable in a wall of a container.
 2. The device according to claim 1, wherein at least one of the emitting devices is an antenna or a patch antenna.
 3. The device according to claim 1, wherein at least a part of the emitting device is arranged essentially rotationally symmetric around at least one emitting device that is centrally arranged in relation to the support element.
 4. The device according to claim 1, wherein at least two of the emitting devices are attached at the same level in relation to a longitudinal axis of the support element.
 5. The device according to claim 1, wherein at least two of the emitting devices are attached at different levels in relation to a longitudinal axis of the support element.
 6. The device according to claim 1, wherein the support element is essentially configured as a circular disk.
 7. The device according to claim 1, wherein the support element has an outer surface with an outer threading.
 8. The device according to claim 1, wherein the support element is sealingly insertable in a wall of the container.
 9. The device according to claim 1, wherein the support element is formed at least in part of a multi-layer ceramic and wherein at least a part of the emitting devices is arranged between the layers of the multi-layer ceramic.
 10. The device according to claim 1, wherein the device has a construction suitable for use in zones at risk for explosion.
 11. The device according to claim 1, wherein the emitting devices are protected by at least one dielectric protective layer.
 12. The device according to claim 1, wherein the support is flange-shaped. 